P0159 OBD-II Trouble Code: Oxygen Sensor (Bank 2 Sensor 2)

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0159 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0159 code

P0159 is a diagnostic trouble code (DTC) for "Oxygen Sensor (Bank 2 Sensor 2)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0159 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0159 trouble code definition

Oxygen Sensor (O2) Circuit Slow Response (Bank 2 Sensor 2)

What the P0159 code means

Code P0159 is a powertrain code that indicates a specific sensor in the exhaust system (bank 2 sensor 2) is not performing as it should. When an oxygen sensor modulates slowly, it is an indication it is bad. This sensor monitors the catalyst efficiency for emissions purposes.

What causes the P0159 code?

This code is set if the oxygen sensor modulates slowly. It should fluctuate between 800mv and 250mv 16 times in a twenty second period. If the sensor does not perform to this standard, it is considered to be bad. Usually due to age or contamination.

Exhaust leaks will set this code as well. Contrary to popular belief, an exhaust leak will suck in oxygen diluting the exhaust flow that will simulate the conditions the computer interprets as a bad oxygen sensor.

This is a four wire sensor with two circuits. If either of these circuits has a short or high resistance, this code could be set as these conditions will affect the oxygen sensor’s ability to perform properly.

What are the symptoms of the P0159 code?

A Check Engine Light. This sensor is mainly for emissions purpose and does not have a significant effect on the performance of the vehicle.

This is a downstream oxygen sensor, meaning it is after the catalytic converter. The computer utilizes downstream oxygen sensors to monitor catalyst efficiency and upstream oxygen sensors to calculate air fuel mixture.

How does a mechanic diagnose the P0159 code?

Technical Service Bulletins (TSB’s) should be checked for problems specific to individual year make and model vehicles.

The computer sets this code after performing some very specific tests. For this reason, a technician having scanned the vehicle and finding this code will likely confirm there aren’t any exhaust leaks before replacing the indicated sensor (bank 2 sensor 2).

If more extensive tests should be necessary, there are variety of methods to do so. A technician can tap directly into the oxygen sensors circuit and observe its function with an oscilloscope. This is usually performed while introducing propane into the intake or creating a vacuum leak and observing how the oxygen sensor reacts to the change in conditions. These tests are often done in conjunction with a test drive.

Resistance tests can be taken with the oxygen sensors connector unplugged from the vehicle's electrical harness. At times, this is done while applying heat to the sensor simulating conditions the sensor would experience when installed in the exhaust system.

Common mistakes when diagnosing the P0159 code

Failing to spot other problems, such as exhaust leaks, vacuum leaks, or misfires are not uncommon. Sometimes other problems can be subtle and easy to miss.

Downstream O2 sensors (O2 sensors after the catalytic converter) exist to make sure the vehicle meets the EPA’s tailpipe emissions standards. Not only does this O2 sensor test the catalyst efficiency, but tests are performed to test the effectiveness of the sensor itself.

The stringent nature of these tests require all other systems to be operating correctly or the results may not be accurate. For this reason, most other codes and symptoms should be addressed first.

How serious is the P0159 code?

This code has a low impact on the daily driving of the vehicle. This is not a system that will make a tow truck necessary.

The seriousness of global warming is what has prompted the EPA and auto manufactures to implement systems such as this.

What repairs can fix the P0159 code?

  • The most common repair is the replacement of the indicated oxygen sensor (bank 2 sensor 2).

  • Exhaust leaks must be repaired before any oxygen sensor is replaced.

  • It is not uncommon to find damaged wiring in the oxygen sensor circuit that would need to be repaired. These circuits are shielded and require extra attention when fixing them.

Additional comments for consideration regarding the P0159 code.

  • Bank 1 is the set of cylinders with number one cylinder in it.

  • Bank 2 is the set of cylinders that does not have number one cylinder.

  • Sensor 1 is the sensor before the catalytic converter which the computer uses to make fuel ratio calculations.

  • Sensor 2 is the sensor that comes after the catalytic converter and is mainly used for onboard emissions testing.

The following conditions must be met for your car to test the health of the bank 2 sensor 2 O2 sensor. This fault detection method may vary between manufacturers and will occur when the following conditions exist:

  • When the car is moving between 20 and 55 miles per hour.
  • The throttle must be open for a minimum of 120 seconds.
  • Operating temperature above 70℃ (158℉).
  • Catalytic converter temperature above 600℃ (1112℉).
  • The evaporative emissions system is purging.
  • The code is set if the oxygen sensor voltage transitions less than 16 times from rich to lean in a 20 second interval.
  • This test utilizes two trip fault detection.

Need help with a P0159 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
trouble codes
P0159

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0159 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,484

Rating Summary
3,176
153
40
23
92
3,176
153
40
23
92

Richard

10 years of experience
415 reviews
Richard
10 years of experience
This is the second time I’ve had Richard work on my car. He always does an outstanding job and is quick, knowledgeable and professional. Highly recommended!!
2012 DODGE CHALLENGER - CHECK ENGINE LIGHT IS ON - LAS VEGAS, NEVADA

Michael

13 years of experience
372 reviews
Michael
13 years of experience
Mike was an absolute professional when he arrived. He walked me thru the whole process of my repairs and also made good recommendations for preventive issues. His mechanical knowledge and good customer services was a breath of air and greatly appreciated :-)
2007 CHEVROLET AVALANCHE - CHECK ENGINE LIGHT IS ON INSPECTION - MARIETTA, GEORGIA

Rodrigo

10 years of experience
85 reviews
Rodrigo
10 years of experience
Rodrigo was exactly on time, very professional and friendly. He assessed my car, let me know the exact problem when a previous mechanic from a shop in my area was unable to. I felt he was very honest and sincere letting me know the level of urgency that I deal with the issue. Absolutely no pressure. I will absolutely use Rodrigo the next time I need anything to do with my car and will tell everyone about him. This is such a great service, I will never go to another mechanic again. It is so convenient. I couldn’t be happier. :)
2013 SMART FORTWO - CHECK ENGINE LIGHT IS ON - LAS VEGAS, NEVADA

Ricardo

8 years of experience
223 reviews
Ricardo
8 years of experience
Great service and was very helpful on what maintenance my vehicle needed and what to expect in the future. Would definitely recommend to anyone and will.
2004 MITSUBISHI LANCER - CHECK ENGINE LIGHT IS ON - LOS ANGELES, CALIFORNIA

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...
The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Shutterstock.com Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...

Related questions

Q: Q: Check engine light on

Hi there. Since the Check Engine Light is on then the computer needs to be scanned for codes first. I usually do this before going any further with it. This can be caused by any number of sensors on the...

Q: Getting 2 then 4 abs codes, brake shutters, speedo dies and engine slowes when Brake and absolutely lights come on,

You definitely want to start by inspecting the front and rear wheel speed sensors; a failure in these circuits will result in several other problems. Begin by connecting a scanner to see if the Powertrain Control Module (PCM) is registering...

Q: When start out driving when accelerate does good to 2000 rpm and then when go to accelerate more it drops off and have to let off

Hello. From what you describe, it would appear that your vehicle is experiencing some sort of engine performance issues. Problems accelerating under load can be caused by many things. A few common causes are issues with the ignition, engine management,...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com